Skeletal Dysplasia: A Case Report

Abstract

This paper presents a rare case of fetal hydrops detected at just 23 weeks of gestation in a 22-year-old woman's first pregnancy. The fetal ultrasound revealed severe skeletal anomalies, craniofacial deformities, and thoracic abnormalities, suggesting a complex and severe skeletal dysplasia, potentially type IA Achondrogenesis-a lethal autosomal recessive condition marked by ossification delay. This case highlights the significance of advanced genetic testing, such as next-generation sequencing (NGS) and whole-genome sequencing (WGS), in diagnosing and understanding skeletal dysplasias. Skeletal dysplasias represent a group of genetic disorders that affect osteogenesis. The prevalence of this condition is 1 in 4000 births. Sadly, 25% of affected infants are stillborn, and around 30% do not survive the neonatal period. There is a wide range of rare skeletal dysplasias, each with its own specific recurrence risk, dysmorphic expression, and implications for neonatal survival and quality of life. When skeletal dysplasia is incidentally discovered during routine ultrasound screening in a pregnancy not known to be at risk of a specific syndrome, a systematic examination of the limbs, head, thorax, and spine is necessary to reach the correct diagnosis. Prenatal diagnosis of skeletal dysplasia is crucial for providing accurate counselling to future parents and facilitating the proper management of affected pregnancies. An accurate diagnosis can be a real challenge due to the wide spectrum of clinical presentations of skeletal dysplasia but advances in imaging technologies and molecular genetics have improved accuracy. Additionally, some of these skeletal dysplasias may present clinical overlap, making it especially difficult to distinguish. After the 11th revision of genetic skeletal disorder nosology, there are 771 entities associated with 552 gene mutations. The most common types of skeletal dysplasia are thanatophoric dysplasia, osteogenesis imperfect, achondroplasia, achondrogenesis, and asphyxiating thoracic dystrophy.

Keywords: hydrops; hypomineralization; micromelia; skeletal dysplasia.

Figure 3

The narrow thorax, pulmonary hypoplasia, and multiple rib fractures are consistent with compromised lung development and potentially respiratory distress. This could be due to limited space within the thoracic cavity caused by severe skeletal abnormalities. These findings further contribute to the overall poor prognosis. (A) Midsagittal section at the level of the thorax and abdomen showing extremely narrow chest. Fetal hydrops, defined as abnormal fluid accumulation in two or more fetal compartments, is a significant finding associated with poor perinatal outcomes [5]; (B) Multiple rib fractures in the axial view of the fetal chest. Pleural effusion.

Figure 1

Assessing long bones on 2D ultrasound reveals signs of shortening, reduction, and extreme bowing, involving the entire limb (micromelia). (A) Fetal legs with remarkably bowed and short femur; (B) Fetal legs with bilateral clubfoot.

Figure 2

Reduced ossification of skull bones and facial abnormalities with a small face, absent nasal bone, and micrognathia. (A) Fetal head with hypomineralisation of the skull bones. Note the large and round head and the skin edema; (B) Fetal profile with a small face, absent nasal bone, and micrognathia.

Figure 4

Patient phenotype shows a flat face, short nose, protruding tongue and eyes, low-set ears, narrow bell-shaped thorax, severe micromelia, bilateral clubfoot, and severe hypomineralisation of the calvaria.